OBJECTIVE Reduction of cognitive function is a possible side effect after the use of cardiopulmonary bypass (CPB) during cardiac surgery. Since it has been proven that piracetam is cerebroprotective in patients undergoing coronary bypass surgery, we investigated the effects of piracetam on the cognitive performance of patients undergoing open heart surgery. METHODS Patients scheduled for elective open heart surgery were randomized to the piracetam or placebo group in a double-blind study. Patients received 12 g of piracetam or placebo at the beginning of the operation. Six neuropsychological subtests from the Syndrom Kurz Test and the Alzheimer's Disease Assessment Scale were performed preoperatively and on day 3, postoperatively. To assess the overall cognitive function and the degree of cognitive decline across all tests after the surgery, we combined the six test-scores by principal component analysis. RESULTS A total of 88 patients with a mean age of 67 years were enrolled into the study. The mean duration of CPB was 110 minutes. Preoperative clinical parameters and overall cognitive functions were not significantly different between the groups. The postoperative combined score of the neuropsychological tests showed deterioration of cognitive function in both groups (piracetam: preoperative 0.19 ± 0.97 vs. postoperative -0.97 ± 1.38, p <0.0005 and placebo: preoperative -0.14 ± 0.98 vs. postoperative -1.35 ± 1.23, p <0.0005). Patients taking piracetam did not perform better than those taking placebo, and both groups had the same decline of overall cognitive function (p = 0.955). CONCLUSIONS Piracetam had no cerebroprotective effect in patients undergoing open heart surgery. Unlike the patients who underwent coronary surgery, piracetam did not reduce the early postoperative decline of neuropsychological abilities in heart valve patients.